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Abstract #3449 Published in IGR 4-2
Effects of dopamine on ciliary blood flow, aqueous production, and intraocular pressure in rabbits
Reitsamer HA; Kiel JWInvestigative Ophthalmology and Visual Science 2002; 43: 2697-2703
PURPOSE: Dopamine is a known modulator of cardiovascular function and intraocular pressure (IOP). In this study, the authors investigate the dose-dependent effects of dopamine on IOP, ciliary hemodynamics, and aqueous production in anesthetized rabbits to test the hypothesis that aqueous production becomes blood-flowBdependent if ciliary perfusion declines below some unknown critical level. METHODS: Two protocols were performed. In the first, mean arterial pressure (MAP) and IOP were measured by direct cannulation, and ciliary blood flow was measured transsclerally by laser Doppler flowmetry, while MAP was varied mechanically over a wide range before and during intravenous dopamine infusion (40 μg/min, n = 8; 80 μg/min, n = 10; 600 μg/min, n = 7; 1800 μg/min, n = 5). In the second protocol, MAP and IOP were measured by direct cannulation, and aqueous flow was measured by fluorophotometry, before and during intravenous dopamine infusion (40 μg/min, n = 8; 600 μg/min, n = 11). RESULTS: The low infusion rate shifted the ciliary pressure flow curves upward and increased aqueous production (40 μg/min), whereas the higher infusion rates shifted the pressure flow curves downward (600 and 1800 μg/min) and decreased aqueous production (600 μg/min). All infusion rates decreased IOP. CONCLUSIONS: Dopamine causes dose-dependent, parallel changes in ciliary blood flow and aqueous production, with ciliary vasodilation and secretory stimulation at the lowest infusion rate and vasoconstriction and secretory inhibition at higher infusion rates. Dopamine also significantly lowers IOP.
Dr. H.A. Reitsamer, Department of Physiology, University of Vienna Medical School, Vienna, Austria
Classification:
5 Experimental glaucoma; animal models
6.11 Bloodflow measurements (Part of: 6 Clinical examination methods)
